Google Code In Task Use coala

GroxNi edited this page Nov 1, 2017 · 83 revisions

Use coala CI on a popular GitHub repository

This is a "beginner" coala GCI repeatable 2016 task coded as "CI1" in GCI.


Use coala CI on a popular GitHub project, of your choice, using a Docker image on Travis CI, and report the results to the coala developers.

This activity is done entirely using a web browser in your own repositories on GitHub, and does not involve interacting with other OSS projects, or installing or using any software on your own computer.

Please do NOT submit any changes to another OSS project in this beginner task. There is a separate GCI task for submitting your changes to other OSS projects, which you can commence after a coala developer has reviewed and accepted your work for this task.


This task assists participants learn about linting and Continuous Integration (CI).


Travis CI runs jobs for each commit in a GitHub repository according to a .travis.yml configuration file, typically used to ensure that every commit is acceptable.

Travis CI can run a Docker, which is a pre-built system image containing pre-configured applications. coala provides a Docker that includes most of the dependencies already installed so that coala can check most file types.

Select a project

Select a GitHub repository

Find a GitHub repository that meets all these criteria:

  1. 100 or more stars,

  2. a Pull Request ''merged'' since 1 October 2016, and

  3. does not use any Continuous Integration.

GitHub Advanced Search can be used to help select a repository that meets those criteria.

To filter out repositories that do not meet the first two requirements, combine

  1. stars:>99, and
  2. pushed:>2016-09-30

The combined query has more than 28,000 repository results, so there are many to choose from.

An optional additional search term is forks:>100 which returns over 11,000 repository results, and these are more likely to be suitable for this task.

On the left hand side of the search results page is a "Languages" selector that you might like to use to restrict the programming language to one that you like. Currently the breakdown is:

Language Repositories
JavaScript 2,326
Java 1,469
Python 1,207
PHP 733
Ruby 685
C++ 648
C 576
Objective-C 431
C# 418
HTML 407

However, you can also find many other languages manually, by adding the language search term, such as Pascal.

Another optional additional search term is size:5000..10000 which restricts the list to repositories of size 5-10Mb. If you have a small Internet bandwidth, a smaller repository is a better choice for when you progress to the second task.

However many popular projects will already be using Continuous Integration, and Travis CI is not the only Continuous Integration provider available on GitHub. We need to check the next criteria manually.

To check whether a repository is using any Continuous Integration, click "Commits" on the front page of the GitHub repository in Desktop mode (it is not visible on the mobile mode).

Beside each commit, there may be an orange, red or green indicator, which informs the reader that a CI routine is in progress, failed or succeeded, respectively.

If there is indicator, the repository has some CI, and is not appropriate for this task.

For example, coala/coala does have these indicators, while the linux kernel does not.

One exception is that sometimes the status indicator is only showing that a publish process was successful, such as the "GitHub Pages" job at github/open-source-survey. This is not Continuous Integration. However note that a GitHub Pages repository that has gh-pages as its default branch is not suitable for this task, as Travis-CI ignores gh-pages branches by default.

Also look for "[username] committed with [software]", which means that the software is controlling the pushes, and typically the software is performing Continuous Integration that is not visible on GitHub.

Finally there is one more manual check. Earlier we used pushed:>2016-10-01 to check if had a recent push, but that is not the same as a recent Pull Request.

To check that a repository has a merged Pull Request in the last month, click on "Pull Requests" on the front page of the GitHub repository in Desktop mode (it is not visible on the mobile mode), and in the text box change is:pr is:open to is:merged and press the Enter key.

This task is limited to only repositories with recently merged pull requests as there are many repositories on GitHub that are a mirror, and the real development occurs somewhere else, and possibly has Continuous Integration already occurring in the real development area, with GitHub only seeing the approved commits.

For example, the linux kernel repository's last merged pull request was 22 April 2014, so it is not eligible for this task.

Another reason for this limit is that the owner of the repository may not be active any more.

Unfortunately GitHub does not allow repositories to disable Pull Requests, so the only way to be confident the project is interested in new Pull Requests is to see whether they have merged Pull Requests recently.

Register your GitHub repository

Only one GCI participant may do this task on any repository. This is to avoid duplicated and wasted effort by GCI participants.

To prevent multiple participants doing this task on the same repository, before continuing each participant must record the repository they have selected in a Google spreadsheet.

First search in that spreadsheet that nobody has selected your repository. If nobody has used it, add a row and fill in the first two columns only, recording your username and your selected repository.

The Google Spreadsheet will automatically save within a few seconds, and you can continue. And then other participants will know to avoid the repository that you have selected for this task.

Fork the repository

On the repository that you have selected, click the fork button.

You should be redirected to your own copy of the same repository on GitHub, with a URL like

Activate Travis CI

Log into using your GitHub account.

To enable Travis CI on your fork of the repository, go to your profile. Then

  1. click "Sync account"
  2. scroll down to find your fork and click beside the grey "X" to make it a blue tick.

Trigger a Travis CI test build

Every time there is a commit to your fork, Travis CI will attempt to build the project, using the configuration in a special file called .travis.yml.

On your GitHub repository page, such as, click "Create new file".

In the file name input box, enter .travis.yml, and in the file contents textarea add the following:

language: generic
    sources: debian-sid
    packages: file
  - file --version || true
  - find . -not \( -path ./.git -prune \) -type f -exec file -N {} + > file.list
  - sed 's/^\.\/\(.*\):/\1:/;s/^.*\/\(.*\):/\1:/;/^[^:]*\..*:/{s/^.*\(\.[^. ]*\):/\1:/;}' file.list | sort | uniq -c | sort -nr

This will list all of the extensions used in the repository, with additional information detected by UNIX file version 5.29.

At the bottom of the page, select "Create a new branch for this commit and start a pull request". It will suggest a new branch name like "[your username]-patch-1". That is OK. Click "Propose new file".

You will be taken to a "Open a pull request" page. This is submitting a Pull Request to your own repository. Click "Create Pull Request".

You will be taken to a "Create .travis.yml" Pull Request, and very soon after a green "All checks have passed" should appear. You can now go to your repository in Travis CI, and see a "green" build. Click on "Show all checks", and then the "Details" links that appears.

You will be taken to a page like this build of sails-docs.

This was just a test build, but you will need that list of extensions later, when you write your report.

Click Back in your browser, and close that Pull Request.

Do NOT merge that Pull Request. Click "Close Pull Request".

Run coala in continuous integration mode

Note: See Local usage for running coala on your own computer.

Create .travis.yml

As installing coala, coala-bears and all of the dependencies is a complex process, the coala team provides a Docker image which has everything installed and ready to be used.

Your .travis.yml will be based on the sample provided in the documentation with experimental automatic .coafile generation.

On your GitHub repository page, such as, click "Create new file".

Fill in the form:

  1. In the file name input box, enter .travis.yml.

  2. In the file contents textarea, add the following

    language: generic
    services: docker
      - touch .gitignore
      - >
        docker run --volume=$(pwd):/app --workdir=/app coala/base:0.9 /bin/bash -c
        "coala-quickstart --ci;
        printf '# Quickstart generated .coafile: ';
        cat .coafile | curl -F 'clbin=<-' 2>/dev/null;
        cat .coafile;
        echo '# End of .coafile';
        coala --ci"
  3. In the "Commit new file" section,

    3.1. In the short commit message text field, add "Add Travis CI using coala CI Docker"

    3.2. Select "Create a new branch for this commit and start a pull request".

    3.3. In the text field under that, replace the sample new branch name with coala-ci-v1.

  4. Click "Propose new file".

You will be taken to a "Open a pull request" page, which you can ignore. You have already created the branch coala-ci-v1, with a commit, which has triggered another Travis CI build.

You can now go to the Travis CI build list and watch your coala CI build occur in real time.

It should look like these (outdated):

Report initial findings

Create a wiki page called "coala Report" in your fork of the selected repository, and copy the following template into the page and then fill in the answers:

# Initial findings

<link to the latest Travis build of your fork>

<link to the generated .coafile on>

Status: Green or Red

## File types

Which file extensions did you enable linting, and which bears were used?

| Ext.  | Bears used
| ----- | -----------
| .*    | FilenameBear, InvalidLinkBear, LineCountBear, LineLengthBear, SpaceConsistencyBear
| .yml  | YAMLLintBear
| .md   |
| .rst  |
| .js   |
| .css  |
| .py   |
| .java |
| etc   |

Which file types are not supported?

<file extensions from your first build which coala-quickstart ignored>

Which file types had errors? ...

## Errors

<paste the sections of the build log which shows the types of linting issues>

If your Travis CI build is 'green', you can not use this repository to do auto-fixing, and so you should skip to the Assessment phase of your task.

Auto-fixing errors

If your Travis CI build is 'red', we can try to use coala --apply-patches to see if the problems can be fixed automatically by coala.

On your GitHub repository page, such as

  1. click "branches",
  2. click on the coala-ci-v1 branch you have created,
  3. click on the file .travis.yml that you created,
  4. click on the "Edit this file" button.

We are going to add coala --apply-patches, and then use git diff to create patch files, and upload them to

Replace the contents of the file with the following:

language: generic
services: docker
  - touch .gitignore
  - >
    docker run --volume=$(pwd):/app --workdir=/app coala/base:0.9 /bin/bash -c
    coala-quickstart --ci;
    coala --ci --apply-patches --no-orig >coala-ci.log
  - git add --all
  # Create two diff files, and upload to
  - >
    git diff --cached --find-renames \
      --ignore-all-space --ignore-blank-lines \
      > sans-whitespace.diff
  - cat sans-whitespace.diff | curl -F 'clbin=<-'
  - git diff --cached --find-renames > with-whitespace.diff
  - cat with-whitespace.diff | curl -F 'clbin=<-'
  # Upload logs to
  - cat coala-ci.log | curl -F 'clbin=<-'

In the "Commit changes" box under the file contents

  1. Set the commit message to "[DNM] Uses coala CI --apply-patches"
  2. Select "Create a new branch for this commit and start a pull request."
  3. In the text field under that, replace the sample new branch name with dnm-coala-ci-auto-patched.
  4. Click "Propose file change".

This will create a commit and trigger another Travis CI build.

It will also load a page called "Open a pull request", which you should ignore.

Extract the patch pastes

Load the Travis build log.

At the end of the Travis build log will be two links to , which contain the sans-whitespace.diff and with-whitespace.diff that were created by the Travis CI build and uploaded to . Download those two files from

Use a programmers text editor to open these patch files. These patches will be using Unix EOL, which some basic Windows text editors, such as Notepad, do not understand.

Upload patches to your repository

On your GitHub repository page, such as

  1. click "Upload files",
  2. Drag-and-drop your patch files to the area provided,
  3. Select "Create a new branch for this commit and start a pull request.", and
  4. Name the new branch 'coala-ci-patches'.
  5. Click "commit".

Auto-fixed results

Create a new section of your wiki page called "Auto-fixes".

Add the two links to this section, and also link to the same files in the coala-ci-patches branch of your repository.

Update your wiki page to briefly describe the problems that were automatically fixed.

Also try to record the types of problems encountered.


The mentors will read your "coala Report", and check your branches on GitHub, and the Travis build logs to verify that you followed the steps above.

You may be asked to redo the process if you deviated from the steps above.

Next task

After satisfactorily completing this task, the next task in this series is advanced "Use coala". If your Travis build was green, you must find another repository to complete the advanced "Use coala" task, as it requires a red build.

If your Travis build was green, you may use this repository for the "Implement coala" task, however you must complete the advanced "Use coala" task first.


Related StackOverflow tags

coala | continuous-integration | lint | static-analysis | git | github | travis-ci | docker | bash |

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